A selective media has been developed for the detection and isolation of Streptococcus mutans from human dental plaque in the presence of other interfering microorganisms (see U.S. Pat. No. 3,890,200, issued June 17, 1975, hereby incorporated by reference in its entirety). The selective media composition for the growth of Streptococcus mutans comprises a solid media selective to induce the growth of the Streptococcus mutans, such as for example a mitis salivarius agar medium. In accordance with the invention described in the patent, the solid media must contain therein a combination of a saccharide compound, such as a mono or di saccharide compound, for example sucrose, fructose or glucose or a combination thereof, together with a selective inhibitory agent such as a polypeptide antibiotic, for example bacitracin, which inhibits the growth of interfering microorganisms, while not impeding the growth of the selective organism of determination. Thus, the saccharide and the antibiotic compounds are present together in a defined concentration insufficient to prevent the growth of Streptococcus mutans on the solid media, but sufficient to prevent the growth in sufficient quantities of interfering microorganisms, such as for example a concentration for the saccharide or from about 5 to 50 percent and the concentration of the antibiotic, such as bacitracin from about 0.01 to 5.0 units per milliliter.
It is desirable to provide a method and test kit for the growth and isolation of Streptococcus mutans and to determine the extent of growth of the Streptococcus mutans in order to provide an indication of the susceptibility of a patient to dental caries. Typically, the method comprises providing a selective media containing the combination of the bacitracin and the saccharide and inoculating the media with a source of Streptococcus mutans then growing and isolating the Streptococcus mutans on the media free of interfering organisms. The selective media for Streptococcus mutans and the method as described in the U.S. patent is both effective and suitable for use in the determination and isolation of Streptococcus mutans in a laboratory environment with trained laboratory personnel. However, it would be most desirable to provide for a simple and effective test kit and method for use by dentists, dental technicians and other health professionals in their office to provide for the semi-quantitative determination of Streptococcus mutans. A simple and effective method that is suitable for semi-quantitative determination out side of the laboratory would be useful in order to provide for a classification of patients into patients of high, intermediate and low dental caries risk. The determination of a high risk patient would enable preventative measures to be taken to reduce the patient's susceptibility to dental caries, such as the use of professional teeth cleaning, variation in diet, flouride treatment, treatment of lesions, direct antibacterial therapy such as the use of chlorhexidine or antibiotics and other preventative or therapeutic treatment.